Screening machine



Dec. 20, 1960 K. MULLER SCREENING MACHINE Filed Nov. 29, 1956 MOE INVENTOR. KURT MULLER ATTORNEYS United States Patent O SCREENING MACHINE Kurt Miiller, 32 Nordstrasse, Recklinghausen, Germany Filed Nov. 29, 1956, Ser. No. 625,102

1 Claim. (Cl. 209-365) tion. Each screen body unit is resiliently mounted by means of a rubber or elastomer member to a transversely extending tube or shaft which is in turn supported at its ends by pendent spring units from the base frames. The

pendent screen supports are mounted for rotational adjustment and also include therein the necessary bumper members of rubber or elastomer that are included in this resonance system. This arrangement permits the screen frame to be oscillated at an adjustable angle.

The invention particularly described herein is in a plurality of units and includes the means for excitation of these units harmonically and the means for oscillating the units in resonance, but particularly including means for selectively varying the angle of oscillation or throw on each particular section of the screen in the plurality of units and the means for coupling or hinging the units together in a manner to permit the oscillation.

This invention further relates to a horizontal screening machine involving what is known as two counteroscillating masses having rubber or elastomer bumpers for conserving the energy of the vibration of a general system known as the Schieferstein system, but incorporating means for adjusting the direction or stroke of the vibratory screen body. The supporting devices would be adjustable so that from a common source of energy exciting each of a number of units in the system, separate screens may be moved at a varying angle.

This is particularly advantageous in a screening operation because as the percentage of fines in the material being screened decreases, the increasingly coarse material can be moved more rapidly along and this can be accomplished by varying the angle of throw from section to section. It will be seen that a lower angle of movement to the vibratory screen body will faci itate more rapid movement of the particles and in the event that the particles are of coal or other materials that may break, the breakage can be substantially reduced and the screening operation facilitated.

An object of this invention is to produce a new and improved combination of a horizontal vibratory screen body of the general type having two counter oscillating masses which incorporates a plurality of components, each of the components having means for varying the angle of throw with respect to the adjacent screen.

A further object of this invention is to combine-the components of a multiple horizontal vibratory screen body of the Schieferstein type having means for adjusting the direction of throw of each of the screen bodies and incorporating means for driving each of the screen bodies at a different angle and for adjusting the relative 2,965,233 Patented Dec. 20, 1960 movements between the base frames and the screen bodies because of this varying screen body movement. 7

Another object of this invention is to incorporatein a multiple section horizontal screening machine of the oscillatory type connection means therebetween to absorb the relative vibration between the screen bodies.

To the accomplishment of the foregoing and related ends, said invention, then, consists of the means hereinafter fully described and particularly pointed out in the claim; the following description setting forth in detail one approved means of carrying out the invention, such disclosed means, however, constituting but one of the various ways in which the principles of the invention may be used.

In the drawings:

Fig. 1 is a longitudinal section of the screening machine;

Fig. 2 is a side view of the screening machine; and

Fig. 3 is a plan or top view of the screening machine.

In general, in connection with horizontal screening machines of the Schieferstein type employing two counter-oscillating masses, it will be seen that there are certain basic characteristics which govern the operation of this screening machine. The entire screening frame or screen box vibrates at an angle of throw to the horizontal that is controlled by the inclination of the pendent springs. It further may be said that the angle of throw is an important factor, and this may be expressed by a, mathematical relationship as in the following equation where each of the components is as follows. It will be noted that the value K, is dimensionless and is a relative value only so that it can be internationally used with metric values as given.

-sin or In general the above equation defines the screen characteristics, particularly the trajectory of the material, and included in this would be the angle of take ofi as the particle leaves the screen momentarily, the angle of impact, the time in flight and the forward travel and, hence, the rate of travel along the screen, as well as the relative impact velocities of the material on the screen surface. It further will be apparent that a screening operation is controlled by a complex set of factors in which part of the particles are being removed, and the particlesthemselves may have certain characteristics of durability, breakup, etc., particu arly in connection with the materials such as coal and the like, but each screen must be adapted to the characteristics of the material being screened, and in this set of components one or more of the components may be varied, as, for example, the vi.- bration frequency and the throw or the angle of throw.

One particularly important characteristic is that asthe screen size changes along the screen, the angle ofthrow should change. The optimum screen efiiciency cannot be achieved in presently known screenin machines of the Schieferstein type because the angle of throw cannot be changed along the screen. In general, the angle of throw must be set to an average value whichunderstandably cannot take into account the highly variable screening properties of the material at the input and output ends. Thus, the material with a wide variation of grain sizes, as, far example, from 0 to 150, requires a comparatively steep angle of throw at the input end of the stream where the finer grain fractions are to be removed in order to eliminate the fines as rapidly as possible. The coarse grains remaining on the screen surface, on the other hand, demand a comparatively small angle of throw at the far end of the stream where the coarse fractions are to be separated so that the coarse grains are not thrown too high and, thus, broken up.

This invention is, then, particularly directed to a new combination in a horizontal screening machine of the oscillatory type employing two counter-oscillating masses in which the screen basically consists of a number of components, each of the components having a screen frame and a base frame fastened together. The individual members of the screen frame exhibit various angles of throw as a result of the differing slope of their pendent springs, and the joints or connections between the screen frame members and the supporting shaft are so constructed to yield in all directions in the plane of vibration.

By means of this combination a new screening machine is developed that adapts the angle of throw to the continuously changing properties of the material traveling along the screening surface and achieves substantially an overall improvement in screening efficiency.

In connection with the drawings, there are six screen frame members indicated at 1 secured to the base frame members 2, of which there are seven components. The members of the screen frame 1 are pivotally secured at their ends by a hinge-like structure to a tubular cross element 3 on both sides adjacent the base frame elements. The securing means is the collar element 4 attached to the cross bar. The preferred connection for these collar elements is by means of a metal-rubber-metal flanged rubber bushing between the cross bars 3 and the collar element 4. These rubber bushing elements yield in all directions in the plane of vibration of the screen frame by distortion of the rubber layer between the cylindrical surfaces. The ends of the cross bar are shown particularly in Fig. 2, which is the side view of this screening machine, and these are supported by means of stifi pendent springs 6 to the base frame element 2. These, in turn, are fastened to a rotatable flange element 9 which is secured to the base frame. It is in this manner that the pitch or throw of the screen may be varied by rotation of the rotatable flange and the repositioning of the angle at which the screen element will oscillate or move with respect to the base frame.

Each of the screen elements may be set at a ditferent angle as is se'en in connection with Fig. 2. At the input end of the screen, and only by way of example, the angle was chosen at 45 and each succeeding element is reduced by until the last element is set at 15 at the discharge end of the screen.

The base frame element is, of course, supported upon a supporting bed consisting of an isolation absorber or spring element 7 to withstand the vibration imparted from the vibratory scereen element to the base frame so that its support members do not vibrate. Each of the base frames are connected together by means of metal-rubbermetal cylindrical rubber bushings which together with other parts serve as an elastic member connector as seen at 8 so that they may yield in all directions in the plane of vibration. It further will be seen that the connecting links or joints 5 are the same type of rubber bushing, and these will accept movement in all directions in the plane of vibration, for slight deviations in the direction of vibration of the individual members, i.e., the base frame and the vibratory screen frame, produced by the differences in the angles of throw.

The particular type of connection shown in the adjustmcnt means, including the spring elements and the bumpers, has been more particularly described in connection with Miiller and Schmidt application Serial No. 457,398, filed September 21, 1954, now Patent No. 2,920,762, dated January 12, 1960. It will be apparent that the flanges 9 rotate precisely about the axis of the cross bar 3. The free ends of the springs 6 are attached to a turret 10 which is mounted on the ends of the cross bar and can rotate and be locked in position on the axis of the cross bar. A pair of energy storing resilient bumper means or recoil butters 11 store the vibration energy of the screen frame and return it to them when the direction of vibration is reversed. The springs 6 are, of course, mounted at right angles to the line passing through the two bumpers.

The screening machine itself is driven through an elastic coupling 12 connected to the first member of the screen frame by a motor 13 mounted in the first base member through an eccentric 14.

Although the present invention has been described in connection with a few preferred embodiments thereof, variations and modifications may be resorted to by those skilled in the art without departing from the principles of the invention. All of these variations and modifications are considered to be within the true spirit and scope of the present invention as disclosed in the foregoing description and defined by the appended claim.

I claim:

In a vibrated screening apparatus of the two counteroscillating mass type, a plurality of screen sections movably connected in end-to-end relation and defining an elongating screening surface for said apparatus, said screening surface having an input end and a discharge end, each of said sections comprising a pair of base frame elements, a screen frame secured therebetween, a connecting means between said screen frame and said base frame comprising a turret, said turret being adjustable relative to said base frame and comprises a pendent spring element attached to the screening frame and turret and incorporating resilient energy storing means thereon capable of absorbing the alternate vibrations of the screen frame and reversing its direction, actuating means for said screen frames from a common source through a direct connection resiliently mounted, said connection to the screen frame comprising a collar element capable of being adjusted relative to said screen frame to permit a rotational motion with respect thereto, said connection providing an elastomer layer to permit vibration between said screen frame sections, each of said turret adjustable means between the base frames and the screen frames being adjusted to position the respective screen frames at different and successively lesser angles with respect to the horizontal and in the direction of material travel along the screening surface, thereby to insure successively lesser angles of throw for the material being screened in passing along the screening surface from the input end to the discharge end thereof, said screen sections moving independently with respect to one another to provide improved separation in screening.

References Cited in the file of this patent UNITED STATES PATENTS 2,020,013 Bailey 7 Nov. 5, 1935 2,168,838 Church et al. Aug. 8, 1939 2,701,061 Kluge Feb. 1, 1955 FOREIGN PATENTS 945,548 Germany July 13, 1956 1,108,347 France Aug. 24, 1955 

